88 HYDROCYANIC-ACID GAS FUMIGATION IN CALIFORNIA. 



extent in fumigation work in California. An examination of the 

 data in this table shows that only Xos. 6523, 6525, 6527, and 6528 

 are suitable for use in fumigation. Each of these is a high-grade 

 article and each contains less than 1 per cent of sodium chlorid. 

 The other three samples contain greatly in excess of 1 per cent. It 

 should be noticed that these last three samples were sold as 98 to 

 100 per cent sodium cyanids. 



Whenever sodium cyanids have been used in the past, the same 

 dosages have been scheduled as for the regular potassium cyanid. 

 Inasmuch as decomposition was then unknown, and no allowance 

 was made for it, the strength of gas giYen off was much less than 

 was belie Yed to be the case. The result has been poor work. This 

 explains the past unsatisfactory work with the "American," or 98 

 to 100 per cent, sodium cyanid. 



THE KIND OF CYANID TO PURCHASE. 



The results of these experiments direct attention to a second 

 consideration in the purchasing of a cyanid. That a cyanid be of a 

 certain grade of purity is no longer the only consideration. It is of 

 equal importance that it be practically free of sodium chlorid. The 

 writer would condemn as unfit for use in fumigation any cyanid 

 containing in excess of 1 per cent of sodium chlorid. 



Returning to a high-grade sodium cyanid, it has been found on 

 analysis of several samples that these contain only a fraction of 1 

 per cent of sodium chlorid. It generally can be held as a safe con- 

 sideration that a cyanid approaching chemical purity will contain 

 not more than a trace of sodium chlorid, and that such a cyanid can 

 be safely used, even though the degree of cyanid purity is alone known. 

 The writer would consider as generally satisfactory for fumigation 

 work a sodium cyanid 124 per cent pure or aboYe. A chemical of 

 lower purity should neYer be used. Preferably the grade demanded 

 should be a little higher than that giYen, or 126 to 130 per cent pure. 

 Absolute chemical purity in a commercial cyanid can not be expected, 

 but cyanids of the degree of purity recommended herein not only 

 are within reasonable limits of expectation but should be demanded. 

 TThen chemicals of this degree of purity are used, analysis for sodium 

 chlorid is unnecessary. It is the lower grade of sodium cyanid — the 

 grade " 100 per cent pure" or less, winch contains the large amounts 

 of sodium chlorid. 



DOSAGES WITH SODIUM CYANID. 1 



All recent dosage recommendations in fumigation have been based 

 on a high-grade potassium cyanid. Such a situation renders it neces- 

 sary to revise our present schedules should we desire to use sodium 



i Whenever sodium cyanid is mentioned in this bulletin, a high-grade article, one 124 to 130 per cent 

 pure, is meant unless otherwise specified. 



